The debate is over: We need to start sucking carbon from the air

If we don’t suck carbon now, life will suck later. That’s
the underlying theme of a report out Wednesday
from the U.S. National Academy of Sciences. The 350-page paper
looks at the prospects for carbon sucking — known to the
fancy-talk types as “negative emissions technologies.”

We not only have to stop turning up the heat with carbon
emissions, but also start turning down the thermostat with negative
emissions technologies, according to the report.

The upshot? The United States should start spending billions to
research negative emissions “as soon as practicable.”

United Nations
Environmental Program

Even before that research is complete, the Academy estimated
that the world could start taking steps right away. Some 10
gigatons of carbon could be removed from the air each year —
about a fifth of all emissions — simply by growing more trees and
taking better care of soil.

As anyone reading Grist knows, temperatures are on track to soar
past the limit (1.5 degrees Celsius of warming) that the global
community has set to dodge the worst consequences of climate
change. The NAS paper follows an alarming study from the United
Nations’ scientific panel that called on the world to take all
manner of solutions to curb warming.

What exactly are these technologies? The NAS report outlines a
few. For starters, walls of fans sucking up air and removing
carbon. Those are already up and running in Iceland and
Switzerland; they’re just expensive to run. Cheaper methods
rely on plants: Fostering mangroves and eelgrass along the coasts,
allowing forests to regrow, and enriching farm soils.

Most of these methods would cost less than $20 per ton of
carbon. That’s about what polluters are charged for carbon
emissions in California and the European Union.

The researchers also studied sucking up carbon with plants, then
burning those plants for energy and capturing the pollution, a
practice known by the un-catchy acronym BECCS “bioenergy with
carbon capture and sequestration.”

BECCS could suck up a lot of carbon, but scaling it would
require burning whole forests and huge fields of crops. If we tried
to snare 10 gigatons with BECCS, that would take the equivalent of
40 percent of global farmland. Erica Belmont, a professor of
engineering at the University of Wyoming who worked on the report,
said her team wanted to estimate how much could be done without
risking hunger and habitat destruction that would come from turning
any farms or forest into carbon-sucking a plantation.

Researchers also examined the possibility of transforming carbon
into stone. That sounds like alchemy, but it’s happening
naturally all the time: Minerals like calcium and magnesium bind
with carbon in the air to form rocks such as calcite, magnesite,
and dolomite. Of all the techniques laid out in the report, this
one has the largest potential.

“You could remove all the carbon dioxide from the atmosphere
many times over if you could bring the rocks to the atmosphere or
the atmosphere to the rocks,” said Steve Pacala, the Princeton
scientist who led the research for this report.

Arguments for developing negative-emission technologies have
stirred up controversy in the past. Critics have said it gives
polluters a pass, permitting them to continue business as usual.
Better to stop putting ever more carbon into the atmosphere, first,
then clean it up later.

But we’ve let carbon pollution rise so much that that this
debate is out of date. “Later” has arrived.